On-line sampling and image analyzer for determining solid content in a fluid media

ABSTRACT

An on-line sampling and analysis system and method in which a sampling line inlet pipe receives a continuous flow of a suspension or a slurry having particulates, such as grains, seed or phosphate rock, for rapid analysis of the contents therein in a flowing stream. A sample presentation area such as a window is positioned below the flow of the suspension or slurry in an assembly allowing for the depositing of a sample of solid content from the suspension or slurry which is collected for viewing by a computer controlled video camera. The camera is provided for imaging the sample of the solid content collected at the sample presentation area, and a personal computer analyzes images provided by the camera to characterize the content of the fluid media. A media flow director positioned in the suspension or slurry flow through the assembly, and above the sample presentation area, generates a vortex for removing the sample of the solid content deposited on the sample presentation area, allowing for the collection of another sample from the suspension or slurry at the sample presentation area. The vortex tube is coupled with associated bypass piping to remove the sample from the system, or return the solid content sample to the flow of the fluid suspension or slurry downstream of the sample presentation area for continuous operation without interruption of the flow in the sampling line. The personal computer provides a user interface for monitoring the content of the suspension or slurry.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to on-line sampling andanalysis of a solid particulate suspended in a fluid, such as aphosphate rock, other minerals, grains, seed and other solids suspendedin water, air, or other liquids or gases. More particularly, theinvention relates to positioning a vortex tube in a process stream abovea sample presentation area such as a light transparent window forremoving deposited particulates, such as phosphates, and allowing forthe collection of subsequent samples, in which the vortex tube providesa bypass to return the particulate samples to the flow downstream of thesample presentation area for continuous operation without interruptionof the flow in the sampling line.

2. Description of the Related Art

Presently, phosphate rock is recovered from a sand-clay mixture that ismined from mineral deposits. Industrial recovery of solids of a fewmillimeters or less, such as phosphate rock, e.g., <1 mm, begins withchemical treatment of a liquid aqueous slurry which includes a longchain hydrocarbon liquid. These hydrocarbons attach to the phosphaterock and are hydrophobic in nature. Thus, after they attach to the rock,the phosphate rock is forced out of the water phase to the surface in anaeration tank called a flotation cell. The flotation cell must bemonitored to ensure maximum recovery of the phosphate rock. Thephosphate content in the slurry exiting the flotation cell after theremoval of the hydrocarbon-bound phosphate rock, also known as tailings,is a representative indicator of flotation cell performance.

Phosphate rock found in the tailings is considered unrecoverable and alost natural resource. Normal operation of the flotation cell involvesoperator estimation of cell performance by visual inspection of thetailings. To optimize the operator's control of the flotation cell, itwould be desirable therefore to provide a system and a method ofcontinuously monitoring phosphate tailings to provide feedback to theoperator to improve the performance and efficiency of the flotation celloperation. To this end, it is usually desirable to maintain the %BPLcontent in the tailings streams below 3% for acceptable cellperformance.

U.S. Pat. No. 5,396,260 to Adel et al. for “Video Instrumentation forthe Analysis of Mineral Content in Ores and Coal” issued Mar. 7, 1995,discloses the determination of mineral content using a video system inwhich digitized images having assigned gray levels are analyzed todetermine the content of particular minerals in a coal slurry determinedfrom the distribution of the gray levels. Slip streams are extractedfrom the tailings and feed lines which are allowed to pass through athin sample chamber with flat glass plates on either side, the samplechamber being enclosed in a light type box with a video camera toprovide a reflected light image for sample analysis. However, such slipstreams extracted from the tailings and feed lines, are not in line withthe tailings stream but merely tapped away from the fluid media beingprocessed and may not be representative of the sampling of an on-lineflowing slurry.

U.S. Pat. No. 4,797,550 to Nelson et al. for “Fiber Optic Detector forFlotation Cell Processing” issued Jan. 10, 1989 discloses a fiber opticdetector submerged in a coal slurry to monitor a coal separationprocess. Light transmitted by an optical fiber is directed toward theslurry, and thus scattered by the slurry, from which a portion of thelight is deflected back to the fiber optic detector, from which thelight intensity reflected by the slurry is used to detect the mineralcontent in the slurry. Accordingly, only a small sample separated fromthe slurry is analyzed, which may not be representative of the on-linestream.

It would be desirable therefore to provide on-line sampling in whichsampling of the particulate content in a fluid media is provided in-linewith the process stream to collect representative particulate samples,such as phosphate rock and sand in a tailings line. An in-line samplepresentation assembly would be advantageous for the collection ofsamples from the tailings where the sample could be returned to a slurrystream for continuous operation without interruption of the flow in thesampling line.

SUMMARY OF THE INVENTION

Typical particulate analysis techniques provide off-line analysis ortapping of relatively small representative samples of the particulatessuspended in a fluid media. These are often difficult to correlate tocurrent process conditions from the resultant data. An on-line analyzerprovides faster and better feedback for adjusting process controlparameters. The apparatus and method embodying the present inventionprovides on-line sampling and analysis of the content of a particulatecomposition having a particle size from about 0.1 to about 20 mm, whichis suspended or slurried in a fluid, which may be a liquid or a gas, toprovide a rapid analysis of the particulate composition. The use of thefluid stream discussed herein is generic to gas and liquid carriermedia. In an important aspect, the invention provides a method andapparatus for the analysis of the phosphate rock content values in aflowing slurry stream. The phosphate analyzer is provided in-line withthe tailings stream of a phosphate floatation process.

In one aspect, the method of invention employs visual light and a visuallight characterizing detection device which uses a visual image of theparticulates, such as grains or seed in suspension or a phosphatetailings slurry, to analyze the particulate sample. The on-line samplingapparatus collects and presents samples that are rapidly purged andresampled using a procedure in which particulate solids in a fluidstream in gas or liquid are accumulated, concentrated or packed in avessel or container for in-line analysis. In another aspect thecharacterizing detection device used to analyze the samples may useX-ray, gamma-ray, neutron, alpha particle, or other radiation sourcesother than visual light where a sample is presented on an area nottransparent to visual light, but which is transparent to the energysource. In a further aspect the characterizing detection device mayemploy magnetic, acoustic, ultra-sound, or other energy sources wherethe particulate sample is presented in a sample presentation area whichis analyzed with the particulate sample packed for the application ofthe associated energy or force. Analysis using electromagnetic energysuch as X-ray, ultra-violet, infra-red or other radiation sources otherthan visual light requires a sample presentation area with a windowtransparent to the energy being used. Another important aspect providesoptical image analysis using a video camera normal to the sampledeposited on the sample presentation area using a computer providingimage processing of the samples. To capture this image, an inlinemechanical delivery vortex assembly presents a representative sample toa video camera. The invention provides a uniform, stationary, andquickly removable particulate sample which is trapped and imaged bypositioning a vortex tube in the process stream above the particulatesample presentation area for thereafter removing deposited particulates.The invention allows for the collection of subsequent particulatesamples, in which the vortex tube provides a bypass to return samples tothe flow downstream of the sample presentation area. In the invention,the particulate sample being analyzed is taken from the continuallyflowing stream of particulates suspended in the fluid media to provide arepresentative particulate sample without interruption of the flow.

According to the invention, the in-line analysis system introduces asample of suspended or slurried particulate composition, such as a sand,phosphate, and water slurry stream into a vortex assembly. The slurrystream gravitationally deposits a particulate layer, such as sand andparticulate phosphate on the bottom of the vortex assembly, which can beviewed through a quartz imaging window. In an important aspect thiswindow is a substantially planar surface to present a sample which has aplanar surface to the characterizing detection device. Pressure-inducingpiping, located downstream of the vortex assembly slightly restricts theflow of this stream, yet permits an uninterrupted flow of slurry throughthe system while allowing the deposited sample to be stationary foroptical detection or analysis during each sampling cycle. In animportant aspect, analysis is done by an imaging technique. When a newsample and sample image is needed, the deposited layer is removed byopening a bypass line around the pressure restriction. The pressurereleased causes a vortex that removes the old sample and allows asubsequent portion of the flow stream to be sampled. When the bypassvalve is closed, the new sample is quickly and uniformly gravitationallydeposited on the quartz viewing glass.

In one aspect, the particulate layer, such as sand and phosphate, isdeposited on the quartz sample presentation area which is transparent orpervious to light. The sample is imaged through this viewing glass witha black-and-white or color video camera. The camera captures stillimages for analysis, and when a new image is required, the bypass valveis opened and closed again. The signal from the camera is captured by aframe grabber computer card which translates the picture into a pixelmatrix image. The computer software determines the average pixelgray-scale or color value, which is compared with a standard associatedwith phosphate content. To verify the correlation, the computer alsoanalyzes individual particle sizes, which information is used to correctthe standard for shifts in gray-scale or color of the particulates whichin the case of phosphates, the sand and slurry matrix may changecontinuously due to the nature of mineral deposits. A computer-userinterface is provided for displaying the current image, the analysesinformation, such as calculated phosphate content, particle sizeinformation, and historical trends.

The invention provides an on-line sampling and image analysis apparatusfor analyzing various compositions of fluid media having suspendedparticulates. The fluid media may be a gas, or in an important aspect, aliquid such as water, and the particulates may include rock, sand orother solid particle content. A media flow director such as the vortexassembly directs the media over the sample presentation area to removethe deposited particulates.

In an important aspect, an on-line sampling and image analysis systemhas an inlet pipe for receiving a continuous flow of a slurriedparticulates. A sample presentation area is positioned below the flow ofthe slurry in an assembly allowing for the depositing of a sample ofparticulates from the slurry which is collected for viewing by acomputer controlled video camera. Gravity settles the particles onto thesample presentation area. The camera images the sample of theparticulate solid deposited on the sample presentation area which is alight transparent window, and a personal computer analyzes imagesprovided by the camera to characterize the particulate composition inthe fluid media. A vortex tube positioned in the flow of the slurriedparticulate through the assembly, and above the sample presentationarea, generates a vortex for removing the sample of the particulatesdeposited on the sample presentation area, allowing for the collectionof a subsequent sample from the slurry at the sample presentation area.The vortex tube is coupled with associated bypass piping to remove theparticulate sample from the flow, or to return the particulate sample tothe flow of the fluid slurry downstream of the sample presentation areafor continuous operation without interruption of the flow in thesampling line. The personal computer provides a user interface formonitoring the phosphate content of the slurry.

Briefly summarized, the present invention is directed to an on-lineparticulate sampling and analysis system and method in which a samplingline inlet pipe receives a flow of a liquid or gas fluid media having aparticulate solid content suspended therein. A sample presentation areais positioned below the flow of the fluid media in an assembly allowingfor the depositing of a sample of the particulates from the fluid media.The sampled solid content is thus collected for viewing in order tocharacterize the particulate solid in the fluid media. In an importantaspect, a vortex tube positioned above the sample presentation areagenerates a vortex for removing the particulate sample deposited on thesample presentation area, allowing for the collection of anotherparticulate sample from the fluid media at the sample presentation area.The vortex tube may be coupled with associated bypass piping to removethe particulate sample from the flow, or to return the particulatesample to the flow of the fluid media downstream of the samplepresentation area for continuous operation without interruption of theflow in the sampling line.

It is an object of the present invention to provide analysis on-linesampling and analysis of a particulate solid content suspended in afluid media that overcomes the disadvantages and problems of the priorart.

It is another object of the invention to provide an on-line sampling andimage analysis system and method for particulate solids, such as thephosphate content in a process stream.

It is a further object of the invention to provide positioning of avortex tube in a process stream above a sample presentation area forremoving deposited particulates allowing for the collection ofsubsequent particulate samples.

It is yet another object of the invention to provide a vortex tubecoupling to a bypass pipe to remove the particulate sample from theflow, or to return particulate samples to the flow downstream of thesample presentation area for continuous operation without interruptionof the flow in the sampling line.

Other objects and advantages of the present invention will becomeapparent to one of ordinary skill in the art, upon a perusal of thefollowing specification and claims in light of the accompanying drawingsand appendix.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an on-line system for determining %BPL analysis ofphosphate rock materials embodying the present invention;

FIG. 2 is the sampling and image analyzing vortex assembly of the systemshown in FIG. 1;

FIG. 3 is a programmable logic controller (PLC) ladder logic program forthe PLC shown in FIG. 1;

FIG. 4 shows a representative image captured for computer analysis fordetermining the level of dark particles in the sample representative ofthe phosphate content in the tailings stream;

FIG. 5 is graph for determining the gray value versus %BPL correlation;and

FIG. 6 shows a personal computer user interface for monitoring thephosphate content of the slurry.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

Referring now to the drawings and especially to FIGS. 1 and 2, FIG. 1shows and on-line system 10 for determining the %BPL analysis ofphosphate rock material embodying the present invention. The samplingsystem 10 performs optical detection, wherein an important aspect of theembodiment employs optical image analysis of particulates such as asolid content suspended in a slurry for sampling in an in-line vortexassembly 12 of the system 10. The imaging and controller electronics arehoused in a separate watertight enclosure 14 which is coupled to thewatertight enclosure of the vortex assembly 12 with dust boot seals,herein Heeco Protecto Boots. Watertight enclosures manufactured by theHoffman Company were found acceptable in the in-line mill and miningapplications described herein. An inlet pipe 16 introduces a liquidslurry to the assembly 12 for receiving the fluid media having solidparticulates suspended therein. The pipe assembly through which thefluid media is directed includes a cavity 18 below the directed flow ofthe fluid media. A sample presentation area, herein a samplepresentation window 20, wherein a sight glass view port provided byQuartz Scientific Inc. positioned at the bottom of the cavity 18, whichmay be formed with the cross pipe 19 of FIG. 2 is provided forcollecting the samples of the solid particulate content from the fluidmedia in the cavity 18 of the pipe assembly for viewing through thesample presentation window 20.

The solid particulate content is collected on the presentation window20, wherein an important aspect of the described embodiment employsgravitational depositing of the sample from the fluid media into thecavity 18 below. A variety of tests indicated satisfactory analysis,e.g. with phosphate rock slurries in water, and seed or grain suspendedin air such as birdseed which included seed of various sizes. Thusgrains on the order of approximately 0.1 to 20 mm may be characterized.A fiber optic light ring 22 is coupled to a light source 24, part numberTQ-F01-1, both the light source 24 and the compatible fiber optic lightring 22 being provided by Micro Optics of Florida for high intensityillumination of the sample with the light ring 22. The imaging camera26, Javelin part number JE3662HR is equipped with a zoom 7000-microzoomlens 27 provided by Micro Optics of Florida provides an appropriateoptical detector, however, other means of optical detection may also beincorporated, such as ultraviolet and infrared lighting and other energysources also may be used for analysis such as that of gamma ray-neutronand magnetic resonance analyzers or the like. Gamma ray-neutronanalyzers such as the Australian Mineral Development Labs (AMDEL)equipment or magnetic resonance analyzing equipment, e.g., a“Phospholyzer” device of Harrison R. Cooper Systems, Inc., AMF Box22014, Salt Lake City, Utah 84122 may be used as characterizingdetection devices.

The light source 24 and imaging camera 26 are coupled to a programmablelogic controller (PLC), herein an Allen Bradley model AB Micrologic 1000PLC control interface, which is further coupled to a computer, herein a200 megahertz Pentium-based personal computer 30 having internal framegrabber hardware. Additionally, a remote operator interface 32 may beprovided for monitoring the in-line sampling and imaging process. ThePLC 28 is coupled to a pneumatic control valve 34 of the vortex assembly12 for controlling the compatible pneumatic pinch valve 36, herein a 1″pneumatic pinch valve 49155K23 provided by Red Valve, Inc. The pneumaticpinch valve 36 of the assembly 12 is coupled with piping 38 to a mediaflow director such as a vortex tube 40 which extends through the flow ofthe fluid media into the cavity 18, above the central presentationwindow 20. The flow of the fluid media to the assembly 12 is providedthrough a primary path in which the differential pressure orifice 42,herein a ceramic ¾″ orifice, or a restricted pipe 43 for limiting theflow through the 2″ pipe of the assembly 12 as the flow proceeds towardsan outlet pipe 44.

The PLC 28 controls the sequencing of the pinch valve 36 to provide abypass of the primary flow through the vortex tube 30 coupled to thepinch valve 36 as an additional flow of the fluid media toward theoutlet pipe 34. One of the indicators, such as warning light 46 may beprovided under control of the computer 30 to indicate an alarm conditionwhen the phosphate content of the liquid slurry exceeds thepredetermined limit identified by analyzing the images of the samples tocharacterize the solid content of the fluid media collected at thesample presentation window 20.

Turning now to FIG. 2, the sample and image analyzing vortex assembly 12provides the media flow director therein which directs a flow 48received in inlet pipe 16 as the fluid media proceeds in the flowdirection to outlet 44 through the assembly 12, the solid particulatecomponents of the slurry fall out of the fluid media into an annulus 50formed by the outer diameter of the vortex tube 40. The inner diameterof the cavity 18 allows the solid particulates to deposit and collect onthe sample presentation window 22 for analysis through a view imagingview port. To this end, the width of the annulus 50 should be no lessthan three times that of the greatest solid particulate so as not toclog the annulus 50 and allow the solid particulates through the annulus50. The positioning of the vortex tube 40 in the cavity 18 is providedwith a steel or glass assembly, or alternatively a cross pipe section 19as in FIG. 2. Thus, as the flow 48 proceeds through the vortex tubeinterconnection and the differential pressure orifice 42 towards theoutlet 44 in the outlet flow direction 52, when the pinch valve 36 isshown as open, the bypass coupled through pipe 38 allows for relativelyhigher pressure flow through the bypass so as to cause a vortex in thevortex tube 40 for removing the sample of the solid particulate contentcollected at the sample presentation window 20. When, however, thepneumatic pinch valve is in its closed position, as shown by referencenumeral 37, the bypass through pipe 38 is inhibited, and the flow 48proceeds directly through its primary path to outlet 44 without thegeneration of a vortex. The timing of the opening and closing of thepinch valve, as indicated by reference numerals 36 and 37, respectively,is sequenced by the PLC 28 providing for rapid repetitive sampling ofthe particulates flowing through assembly 12. This periodic sampling maybe provided on the order of seconds, specifically 3 second samples, butthe timing may be increased to provide sampling on the order of minutes,described further below in connection with the personal computerinterface of FIG. 6.

As described, the differential pressure provided between the bypass andthe primary flow direction of the fluid media out towards the outletpipe 34 allows for the generation of the vortex in the vortex formingtube 40 of the apparatus 12 when the bypass 38 coupled to the pneumaticpinch valve is opened. A need for providing the differential pressurebetween the bypass and primary path, such as the differential pressureorifice 42 or a restrictive portion of a piping in the primary pathprovides for the differential pressure allowing for the creation of thevortex in the tube 40 as the flows exit the system 10 in the flowdirection 52 of the assembly 12. Accordingly, the tube 40 forming thevortex is coupled for returning the sample of the solid contentcollected within the cavity 18 on the sample presentation window 20 tothe fluid media 52 at the outlet pipe 44 downstream of the samplingcavity 18. Thus, the PLC 28 under control of the computer 30, controlsthe camera 26 and the pneumatic pinch valve 36 for sequencing theoperation of the system 10 for removing the deposited solid particulatecontent samples allowing for the collection of subsequent samples inwhich the vortex tube 40 provides a bypass via pipe 38 to return thesamples to the flow 52 downstream of the sample presentation window 20for continuous operation without interruption of the flow in thesampling line.

To this end, a programmable logic controller ladder logic program forthe PLC 28 is shown in FIG. 3, in which the sequencing of the latchingof a start signal 60 initiates the timing provided by the PLC 28. Atreference 62 of the ladder logic, an output signal is provided forindicating the pinch valve open command which is followed by a settlingtime provided at 64. Following the settling time of approximately twoseconds, an image ready command is initiated as an output signal fromthe PLC 28 at reference 66. An analytical wait timer 68 is provided inthe PLC 28 ladder logic for allowing the personal computer 30 to performthe necessary analysis on the acquired image sample. Subsequentprocessing of the ladder logic program indicated in FIG. 3 provided forcontinuous acquisition of samples and analysis in the system 10, asdescribed.

During the sampling process, the computer 30 and air valve 36 operationsare timed in FIG. 3 in order to capture still images for analysis. Whenthe valve 36 is open, a new sample is being obtained as the camera 26images a swirling motion. When the valve is closed, the slurry stopsswirling and rapidly settles by the forces of gravity on the sight glass20. To capture an accurate image, the frame grabber inside the computer30 acquires the image after the solid particulates, e.g., sand, settleson the sight glass 20. To synchronize the time between the computer 30and valve 36, the design programmed the PLC 28 to operate in four areasof timing. The first time delay represents the time the valve is openand acquiring a new sample. The second time delay is used to allow thesolids to settle on the sight glass 20. During the third time delay, thePLC 28 sends a signal to the computer 30, via the serial port, toindicate that an image is ready to be captured. The fourth time delayrepresents a buffer period when the PLC 28 stops sending the signal tothe computer 30 while the valve 36 remains in closed position 37. Thisbuffer period protects the computer 30 against the possibility ofgrabbing an image when the valve 36 is beginning to open. These fourtime delays are run in an infinite loop on the PLC 28. Of these fourdelays, the first and second are the longest. This is due to the timenecessary to ensure a new sample is obtained and the slurry settles onthe sight glass 20. The third and fourth time delays are short since theframe grabber captures an image very quickly. The total cycle time iscurrently three seconds but may be extended minutes, hours, days, etc.This time was chosen as a balance between reliable statistics andminimal wear to the system 10.

In the invention, the overall analysis process of particulate materialcan be broken down into four parts: the physical acquisition of theparticulate sample, control of the acquisition mechanism, the imagecapture, and the image analysis. The following description will bedirected to describing the percentage of phosphate in a particulatecomposition which is an important aspect of the invention. The in-linedetermination of phosphate rock percentage begins with redirecting aportion of the phosphate slurry to the sampling apparatus. The waterbased slurry contains between 10 to 50 percent solids and has a particlesize of from about 0.1 mm to about 1.0 mm. The sampling apparatus allowsthe solids to settle from the slurry so that an image of the settledparticulates on the presentation window can be captured. After vortexsweeping of the sample window, the sample is then replaced by another.This process repeats about once every three to ten seconds. Theacquisition rate is controlled by the PLC 28. The sample is photographedby camera 26 as a color-analog video image, while lit by a highintensity light. The image is transmitted to a video capture cardinstalled in the computer 30. The capture card grabs the image andstores it in RAM for processing. The image processing program determinesthe phosphate content by performing a gray scale histogram. The lastfifteen results are averaged and the phosphate content is reported onceevery minute. The results are saved to hard drive.

As described, the vortex sampler assembly is constructed ofabrasive-resistant piping 38, a sight-glass assembly 20, a pressureorifice 42 or restrictive pipe 43, and the actuating valve 36 for sampleacquisition and control. The slurry flow stream 48 travels through atwo-inch inside diameter (ID) pipe 16 to the sight glass assembly cavity18 and sample presentation window 20. The flow travels around the vortextube 40 and out of the sight glass assembly to the pressure orifice 42.When a new image is required on the sight glass imaging window, thebypass valve 36 is opened which redirects the flow through the vortextube 40 for picking up and sweeping away the sample. This redirection iscreated by the pressure differential across the orifice 42. The flowpath of this redirected flow causes a vortex to form above the imagingwindow. This vortex ensures a fast and complete removal of the oldsample from window 20. The rapid deposition of the next image sample isfacilitated by the change in flow direction when the valve is returnedto the closed position 37. The closing of the bypass valve above theimaging window 20 causes the vortex to stop immediately and the sampleto deposit into the stagnation zone of the sight glass assembly. The newimage is ready to be captured. The total cycle time for vortex samplerassembly is approximately three seconds.

The sample acquisition mechanism is controlled by the PLC 28 whichincludes a microprocessor having ten inputs and eight relayed outputs.The PLC package comes with a hand-held programmer unit to program themicroprocessor. The computer 30 communicates with the PLC by means of anRS-232 cable. The computer portion providing image capture and analysishardware of the system can be further broken down into two main areas,the computer and frame-grabber. The software was written in the computerprogramming language which is conventional to such applications. Thefirst program obtains the gray scale analysis of an image and could beautomated. Additionally, Visual Basic was used to achieve an acceptableinterface as well as the ability to analyze images. The Visual Basic cancall C routines which run much faster, Visual Basic can be upgraded toversion 5 which is supposed to be faster, or if a fast enough computeris obtained speeding up program execution might prove unnecessary.

In the evaluation of frame-grabbers, the Matrox Meteor was chosen. Thiscard has the necessary speed, comes with a basic software developer kitallowing it to be controlled by Visual Basic, and has a powerful imageanalysis library. In addition, the Matrox Meteor supports up to fourcameras at once. This allows upgrades for multiple camera applications.The number and size of phosphate particles and changes in sand matrix asshown in image 70 of FIG. 4 alter the mean gray scale values, and theblob analysis of these changes was incorporated into the software sincethe color bin distribution analysis was specialized in the way that itapproached the problem. The human eye detects the black particles in apicture by clarifying the relative intensities at the boundaries. Theroutines are based on reading the image into a 640×480 array andmanipulating the entire picture. Thus, phosphate content was determinedusing an integrated blob analysis into the analysis routines.

A blob analysis routine was based on several available resources. Theprocedure calls for an edge detection filter to pass through thecaptured image 70. This filter looks for changes in the gradient andproduces an image that has the dark patches outlined. The filterspecifically takes advantage of the 256 gray shade range. The filteralso utilizes a minor thresholding to obtain the outlined result. Thenext step in the procedure calls for a chain function to trace throughthe outlines and count the outlines that form complete loops. Theseloops are counted as blobs and the directions around the blobs arerecorded. Another function determines the area of each blob by followingthe recorded directions (in a manner very similar to calculating thearea under a curve). Since all blobs are not clean images, some are notfound with the first pass of the chain function. Another function wasadapted for the express purpose of cleaning up the remaining images. Itspecifically enters the interior of the remaining blobs and traces theinside of a blob where there is less visual noise.

Due to the long amount of time required for a chemical analysis oftailings sample, a dependable correlation between blob area andphosphate content was never obtained. To circumvent this limitation, acalibration procedure was introduced. The calibration button first grabsa series of pictures and performs the blob analysis routine on them. Theresult of this routine is written to disk. After the chemical analysisof the samples is obtained, the operator can input the BPL value intothe calibration routine.

The calibration curve of FIG. 5 shows an r² value of 0.9807 for a linearfit of the experimental data under tight camera control. A similarcorrelation was tested for the median gray scale value. The mean waschosen for its sensitivity to skewed data. The mean gray value wasdetermined for samples ranging from 0.6 to 16.2% BPL. This curve workedreliably for the bench scale model. The data is highly dependent uponinformation from calibration standards rather than individual images.With mean gray scale, the background is just as important as the blackparticles. This background color was discovered to change with samplematerial from different mining sites. Operator calibration was added tothe software as a means of quickly adjusting this sensitivity. The slopeof the correlation was assumed to be constant, whereas the intercept (ormean gray value of a pure sand image) could be changed whenever theoperator calibrated the system. It was determined that a calibrationbetween the blob areas and %BPL was a more accurate estimation ofphosphate content.

In the blob analysis discussed above and provided as software programlisting Appendix A, the image is scanned across each row until a blackpixel is found. The chain code begins to search within a one-pixelneighborhood for another black pixel. The direction to each subsequentblack pixel is recorded into the direction array and the previous pixelis erased so that it will not be found again. If no black pixel isfound, the code searches for the darkest gray pixel in the same region.It was observed that one-pixel gaps occurred due to the thresholding inthe filter. Lesser gradients were still passed through the filter asgray pixels. Chains that returned to their original pixels wereconsidered blobs.

FIG. 6 shows a personal computer user interface for monitoring thephosphate content of the slurry in a Windows PC environment. Inparticular, the computer screen 72 provides an image window for viewingthe solid particulates being imaged 70. Running averages, hereinrespectively 1 minute and 10 minute running averages of the %BPL contentin the tailing stream are indicated at reference numerals 74 and 76,respectively. The computer user interface 72 additionally includes anumber of soft buttons, in particular a calibration button 78, reportgeneration 80, exit 82 and pause 84. The sample group number isindicated in the lower left hand corner of the screen at reference 86,and the image of the group is identified by the image number 88, hereinimage number 13 being presented as the image 70 of the computer screen72. The %BPL graph for the last two hours of operation is indicated atthe lower portion of the computer screen as graph 90; as shown the graph90 indicates a gradually decreasing %BPL content over time. Typically,it is desired that the %BPL be maintained below 3%, and thus the graph90 provides a useful user interface for indicating when an alarmcondition may be about to occur. As discussed above, light 46 is apower-on indicator for the PLC/camera unit, additionally the personalcomputer interface provides an alarm in number 92 which may change froma green color for proper operation to a red color to indicate a %BPLhigher than what is desired, e.g., higher than 3%. As described, thecomputer user interface provides a useful interface for the operator toascertain the trend of the tailing stream, and to allow for promptcorrective operation of the flotation cell for optimal performance.

While there has been illustrated and described a preferred embodiment ofthe present invention, it will be appreciated that modifications mayoccur to those skilled in the art, and it is intended in the appendedclaims to cover all those changes and modifications which fall withinthe true spirit and scope of the present invention.

What is claimed is:
 1. An on-line sampling and image analysis system,comprising: an inlet pipe for receiving a flow of a fluid media havingparticulates suspended therein; a sample presentation area positionedbelow the flow of the fluid media upon which a sample of theparticulates from the fluid media is collected for viewing; a tubepositioned in relation to said sample presentation area for removing thesample of the particulates deposited on said sample presentation area; amedia flow director at said tube for directing the media over the samplepresentation area for removing the sample of particulates away from saidsample presentation area; and an outlet wherein said media flow directorreturns the particulate sample collected at said sample presentationarea to the fluid media at said outlet.
 2. A system as recited in claim1 wherein said media flow director is positioned above said samplepresentation area.
 3. A system as recited in claim 2 wherein said mediaflow director lifts the particulate sample away from said samplepresentation area.
 4. A system as recited in claim 1, comprising acharacterizing detection device using an energy source to characterizethe particulates of the fluid media, wherein the sample presentationarea is pervious to the energy source employed.
 5. A system as recitedin claim 4, wherein the energy source comprises a light source forilluminating the sample presentation area, and wherein the samplepresentation area comprises a window transparent to visible light.
 6. Asystem as recited in claim 4, wherein the sample presentation areacomprises a substantially planar surface to present the sample as havinga planar surface to the characterizing detection device.
 7. A system asrecited in claim 1, wherein the sample presentation area is a windowtransparent to light and the system further comprises: a camera forimaging the sample of the particulates collected at said samplepresentation area; and a computer for analyzing images provided by saidcamera to characterize the particulates of the fluid media.
 8. A systemas recited in claim 7, wherein said window comprises a substantiallyplanar surface to present the sample as having a planar surface to theimaging camera.
 9. An on-line sampling and image analysis system,comprising: an inlet pipe for receiving a flow of a fluid media having asolid content; a sample presentation window positioned below the flow ofthe fluid media upon which a sample of the solid content from the fluidmedia is collected for viewing; a tube positioned above said samplepresentation window for generating a vortex for removing the sample ofthe solid content deposited on said sample presentation window, whereinsaid tube for generating the vortex is positioned within the cavity ofsaid pipe assembly extending above said sample presentation windowthrough the flow of the fluid media defining an annulus in the cavityfor receiving the sample of the solid content from the fluid media; andan outlet pipe through which the flow of the fluid media leaves thesystem, wherein said tube for generating the vortex is coupled to abypass pipe for returning the sample of the solid content collectedwithin the cavity on said sample presentation window to the fluid mediaat said outlet pipe.
 10. A system as recited in claim 9, wherein saidinlet pipe receives a fluid-solid mixture having phosphate and sandcontent.
 11. A system as recited in claim 9 comprising a pipe assemblythrough which the fluid media is directed, said pipe assembly includinga cavity below the directed flow of the fluid media, said samplepresentation window being positioned at the bottom of said cavity forcollecting the sample of the solid content from the fluid media in thecavity of said pipe assembly for viewing.
 12. A system as recited inclaim 9 comprising means for providing a differential pressure betweensaid bypass pipe and the flow of the fluid media towards said outletpipe for generating the vortex in said tube coupled to said bypass pipe.13. A system as recited in claim 9 comprising a differential pressureorifice in the flow of the fluid media towards said outlet pipe fordecreasing the pressure from fluid flow through said bypass pipe.
 14. Asystem as recited in claim 9 comprising a pinch valve in said bypasspipe for actuating the vortex in said tube coupled to said bypass pipe.15. A system as recited in claim 14, further comprising: a camera forimaging the sample of the solid content collected at said samplepresentation window; and a computer for analyzing images provided bysaid camera to characterize the solid content of the fluid media.
 16. Asystem as recited in claim 15 comprising a programmable logic controller(PLC) coupled to said computer, said camera, and said pinch value forsequencing the operation of said system for removing deposited solidcontent samples allowing for the collection of subsequent samples inwhich the vortex tube provides a bypass to return samples to the flowdownstream of the sample presentation window for continuous operationwithout interruption of the flow in the sampling line.
 17. A system asrecited in claim 9 wherein said sample presentation window comprises aquartz sight glass, said system further comprising a fiber optic ringlight source for illuminating said sample presentation window forimaging the sample of the solid content collected with said camera. 18.An on-line sampling and image analysis method, comprising the steps of:receiving a fluid media having a solid content; collecting a sample ofthe solid content from the fluid media at a sample presentation area;imaging the sample of the solid content collected at the samplepresentation area; analyzing images provided by the imaging step tocharacterize the solid content of the fluid media collected at thesample presentation area; generating a vortex for removing the sample ofthe solid content from the sample presentation area, allowing for thecollection of another sample of the solid content from the fluid mediaat the sample presentation area by said collecting step; and returningthe sample of the solid content to the fluid media with an outlet fromthe sample presentation area.
 19. A method as recited in claim 18comprising the step of returning the sample of the solid contentcollected by said collecting step to the downstream flow of fluid media.20. A method as recited in claim 18, wherein said receiving stepreceives a liquid slurry having phosphate and sand content.
 21. A methodas recited in claim 20 comprising the step of indicating an alarmcondition when the solids content of the fluid stream exceeds apredetermined limit identified by said analyzing step.
 22. An on-linesampling and image analysis system, comprising: means for receiving afluid media having particulates solid suspended therein; means forcollecting a sample of the solid content from the fluid media; means foroptically detecting the sample of the solid content collected at saidmeans for collecting; means for analyzing the optically detected dataprovided by said means for imaging to characterize the solid content ofthe fluid media; means for generating a vortex for removing the sampleof the solid content collected at said means for collecting; and anoutlet wherein said vortex generating means returns the sample of thesolid content collected at said means for collecting to the fluid mediaat said outlet.
 23. A system as recited in claim 22, wherein saidreceiving means receives a gas having a solid content.
 24. A system asrecited in claim 22, wherein said receiving means receives a liquidhaving a solid content.
 25. A system as recited in claim 22, whereinsaid vortex generating means sweeps the sample of the solid contentcollected from said means for collecting.